Vineland Adaptive Behavior Scales are a valid and reliable test to measure a person's adaptive level of functioning. Vineland-II forms aid in diagnosing and classifying intellectual and developmental disabilities (IDD, formerly known as mental retardation) and other disorders, such as autism spectrum disorders and developmental delays. As with the current Vineland, the content and scales of Vineland-II were organized within a three domain structure: Communication, Daily Living, and Socialization. This structure corresponds to the three broad Domains of adaptive functioning recognized by the American Association of Mental Retardation (AAMR, 2002): Conceptual, Practical, and Social. In addition, Vineland-II offers a Motor Skills Domain and an optional Maladaptive Behavior Index to provide more in-depth information

The VABS are useful in assessing an individual’s daily functioning. They
can be used as an evaluation and diagnostic tool for individuals who have a mental disability or individuals with other handicaps. They can also be
used to develop individual educational, rehabilitative, and social work treatment
programs and can monitor progress during such a program. Finally, the
VABS can be used in research in which the development and functioning
of handicapped and non-handicapped individuals are investigated

Adaptive behaviors are everyday living skills such as walking, talking, getting dressed, going to school, going to work, preparing a meal, cleaning the house, etc. They are skills that a person learns in the process of adapting to his/her surroundings. Since adaptive behaviors are for the most part developmental, it is possible to describe a person's adaptive behavior as an age-equivalent score. An average five-year-old, for example, would be expected to have adaptive behavior similar to that of other five-year-olds.

Behavior problems, often called maladaptive behaviors, are behaviors that interfere with everyday activities. Good adaptive behavior and a lack of behavior problems promote independence at home, at school, and in the community. Behavior problems are much more difficult to quantify than adaptive behaviors are, because they are not very developmental and because their expression varies more from day-to-day and from setting-to-setting. Behavior problems do not increase or decrease steadily with age. Nevertheless they can be measured reliably. The evidence based approach to treating Behaviour problems is functional behaviour assessment(FBA). FBA requires direct observation of individual problem behaviour and experimental manipulation of environmental variables to determine the functional relationship between behaviour and environment for an individual. Unlike direct observation methods, the Vineland is an indirect instrument and of limited applicability to functional behaviour assessment for individual behaviour problems{{cn}.

The purpose of measuring adaptive and maladaptive behavior is usually either for diagnosis or for program planning. The diagnosis of mental retardation, for example, requires deficits in both cognitive ability and adaptive behavior, occurring before age 18. Adaptive behavior assessment is also used to determine the type and amount of special assistance that people with disabilities may need. This assistance might be in the form of home-based support services for infants and children and their families, special education and vocational training for young people, and supported work or special living arrangements such as personal care attendants, group homes, or nursing homes for adults. Adaptive behavior assessments are often used in preschool and special education programs for determining eligibility, for program planning, and for assessing outcomes.

Reliability: 1) Split half-reliability: Internal reliability tests of both the
Survey and Expanded Forms were performed on caregivers of children
under age 19. The Survey Form split half coefficients for the age groups
under 3 ranged from .82 to .95 for the Domains and .96 to .98 for the
Adaptive Behavior Composite; the Expanded Form split half coefficients
ranged from .90 to .97 for the Domains and .98 to .99 for the
Composite. (2) Test-retest reliability (mean of 17 days between tests):
The Survey Form reliability coefficients for caregivers of children
between the ages of 6 months and 2 years, 11 months ranged from .78
to .92 for the Domains and .90 for the Adaptive Behavior Composite.
There were no test-retest reliability tests for the Expanded Form. (3)
Interrater reliability: The Survey Form interrater reliability coefficients,
with a mean of 8 days between the interviews of caregivers of children
ages 6 months to 18 years, 11 months, ranged from .62 to .78 for the
Domains and was .74 for the Adaptive Behavior Composite. There were
no interrater reliability tests for the Expanded Form.

Validity:
(1) Content validity included a literature review and field tests
with caregivers.
(2) Criterion-related validity: The correlations between
the Adaptive Behavior Composite and the original VABS unadjusted
Social Quotient and Silverstein’s Deviation Social Quotient (which
corrects for inconsistencies in the Social Quotient) among caregivers of
children between ages 6 months and 18 years, were both .55.
Comparisons between the total of the raw scores for the four domains of
the revised VABS and the original VABS yielded a correlation of .97 in a
sample of mentally retarded adults and an age-adjusted partial
correlation of .88 in a sample of hearing-impaired children. The
correlation between the VABS and the Adaptive Behavior Inventory for
Children, ages 5 to 11, was .58, and correlations between the revised
VAB four domains and the AAMD Adaptive Behavior Scale, Part I,
domains fell between .40 and .70.
Correlations between VABS and the Kaufman Assessment Battery for
Children and the Peabody Picture Vocabulary Test-Revised, two
intelligence tests, ranged from .07 to .52 and .12 to .37, respectively.
The differential magnitudes of these correlations is said to support the
assumption that adaptive behavior scales and intelligence and
achievement scales measure different areas of functioning.

There is a significant amount of research that uses the Vineland as a measure. For example, one study found that children with Complex Trauma and a diagnosis of Reactive attachment disorder showed significant developmental delays as measured by the Vineland[1]

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